Rani can name $48$ world capitals. She can name $21$ fewer than Ari can. How many world capitals can Ari name?
Explanation: To find the ${\text{total}}$ number of capitals Ari can name, we start with the number of capitals ${\text{Rani}}$ can name, and add how many ${\text{fewer}}$ names she can name than Ari. $?$ $48$ $21$ Ari Rani fewer names $\begin{aligned} {\text{Rani}} + {21} &= {\text{Ari}} \\\\ {48} + {21} &= {\Box} \end{aligned}$ Let's add to find the total number of capitals Ari can name. $$ $$ $$ $$ $$ $$ ${+}$ $$ $$ $$ ${=}$ $$ $$ $$ $$ $$ $$ $$ $$ ${48} + {21} = {69}$ Ari can name ${69}$ world capitals.